Abstract: Many people follow Grice in thinking that all conversational implicatures are cancellable. And often enough they use this insight as a test for conversational implicatures. If one wants to find out whether something is a conversational implicature, the test goes, one should ask oneself whether the thing in question is cancellable; if one finds that it is not cancellable, one can infer that it is not a conversational implicature; if one finds that it is cancellable, one can infer that it might well be a conversational implicature and conclude that one should now do further testing. Various philosophers and linguists have questioned the test, though. Some have held that Grice's original claim is subject to counterexamples and that the test is therefore prone to failure. Others have argued that even though Grice's claim can be defended against the counterexamples, the test turns out to be useless. In this paper, I shall defend Grice's test. I shall not only argue that given the right view of cancellability all conversational implicatures are cancellable; I shall also show that given this view the test can be usefully applied.